[POC; Not for Review] Don't use PostTask queueing between compositor and main thread.

content/renderer/input/main_thread_event_queue.h

Index: content/renderer/input/main_thread_event_queue.h
diff --git a/content/renderer/input/main_thread_event_queue.h b/content/renderer/input/main_thread_event_queue.h
index 6a99636a9a0d2f0851d7404b89778eb676a733a8..3284bbbe62a1271d837f8fa2736ead7451cab0d8 100644
--- a/content/renderer/input/main_thread_event_queue.h
+++ b/content/renderer/input/main_thread_event_queue.h
@@ -11,6 +11,7 @@
 #include "content/common/input/input_event_ack_state.h"
 #include "content/common/input/input_event_dispatch_type.h"
 #include "content/common/input/web_input_event_queue.h"
+#include "ipc/message_filter.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/events/latency_info.h"
 
@@ -43,15 +44,19 @@ using PendingMouseWheelEvent =
 using PendingTouchEvent =
     EventWithDispatchType<TouchEventWithLatencyInfo, blink::WebTouchEvent>;
 
+using PendingMouseEvent =
+    EventWithDispatchType<MouseEventWithLatencyInfo, blink::WebMouseEvent>;
+
 class CONTENT_EXPORT MainThreadEventQueueClient {
  public:
-  // Send an |event| that was previously queued (possibly
+  // Handle an |event| that was previously queued (possibly
   // coalesced with another event) to the |routing_id|'s
   // channel. Implementors must implement this callback.
-  virtual void SendEventToMainThread(int routing_id,
-                                     const blink::WebInputEvent* event,
-                                     const ui::LatencyInfo& latency,
-                                     InputEventDispatchType dispatch_type) = 0;
+  virtual void HandleEventOnMainThread(
+      int routing_id,
+      const blink::WebInputEvent* event,
+      const ui::LatencyInfo& latency,
+      InputEventDispatchType dispatch_type) = 0;
 };
 
 // MainThreadEventQueue implements a series of queues (one touch
@@ -92,7 +97,11 @@ class CONTENT_EXPORT MainThreadEventQueueClient {
 //
 class CONTENT_EXPORT MainThreadEventQueue {
  public:
-  MainThreadEventQueue(int routing_id, MainThreadEventQueueClient* client);
+  MainThreadEventQueue(
+      int routing_id,
+      MainThreadEventQueueClient* client,
+      const base::Callback<void(const IPC::Message&)>& main_listener,
+      const scoped_refptr<base::SingleThreadTaskRunner>& main_task_runner);
   ~MainThreadEventQueue();
 
   // Called once the compositor has handled |event| and indicated that it is
@@ -109,12 +118,29 @@ class CONTENT_EXPORT MainThreadEventQueue {
   void set_is_flinging(bool is_flinging) { is_flinging_ = is_flinging; }
 
  private:
+  void QueueWheelEvent(const PendingMouseWheelEvent& event);
+  void QueueTouchEvent(const PendingTouchEvent& event);
+  void QueueMouseEvent(const PendingMouseEvent& event);
+  void SendWheelEventNotificationToMainThread();
+  void SendTouchEventNotificationToMainThread();
+  void SendMouseEventNotificationToMainThread();
+  void PopTouchEventOnMainThread();
+  void PopWheelEventOnMainThread();
+  void PopMouseEventOnMainThread();
+  void SendEventToMainThread(const blink::WebInputEvent* event,
+                             const ui::LatencyInfo& latency,
+                             InputEventDispatchType original_dispatch_type);
+
   friend class MainThreadEventQueueTest;
   int routing_id_;
   MainThreadEventQueueClient* client_;
   WebInputEventQueue<PendingMouseWheelEvent> wheel_events_;
   WebInputEventQueue<PendingTouchEvent> touch_events_;
+  WebInputEventQueue<PendingMouseEvent> mouse_events_;
   bool is_flinging_;
+  base::Lock event_queue_mutex_;
+  scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
+  base::Callback<void(const IPC::Message&)> main_listener_;

[tdresser, 2016/05/30 14:05:32]

Eventually we'll want a couple ThreadChecker's in here.

https://code.google.com/p/chromium/codesearch#chromium/src/base/threading/thr...

[dtapuska, 2016/06/01 18:22:54]

Acknowledged.

 
   DISALLOW_COPY_AND_ASSIGN(MainThreadEventQueue);
 };